I setup a L2TP/IPsec VPN on version 6.46.7. I have 2 Windows 10 systems, one connects without problems. The other gives me this error. Both are on the same local network.

Can't connect to. . .
The L2TP connection attempt failed because the security
layer encountered a processing error during initial
negotiations with the remote computer.

The router log doesn't show any connection attempt. Any thoughts where to look?